In the prior art, a diaphragm construction method is applied to steel pipe columns here and there of a building structure for reinforcement and deformation prevention purposes, in many cases. In a through diaphragm construction method as one of such diaphragm construction methods, the steel pipe column is cut to match upper and lower flanges of the steel H-beam, and a diaphragm is inserted and welded to the steel pipe column, so that they are assembled. The steel H-beam is installed by cutting out a portion for connecting to the steel pipe column as a beam bracket in advance, welding the upper and lower flanges to the through diaphragm, and welding its web to a skin plate of the steel pipe column. The beam bracket installed in the diaphragm and the steel H-beam are joined to each other using a high-strength bolt friction connection.
In this through diaphragm construction method, a process of welding the diaphragm to the steel pipe column is added to the process of cutting the steel pipe column. In particular, this welding process necessitates perfect penetration welding around the entire circumference of the steel pipe. For this reason, an inspection of the welded portion is necessary in addition to the cutting process and the welding process. This disadvantageously increases a work burden necessary for the manufacturing. Furthermore, a well-skilled welding engineer is necessary in order to secure quality in the welded portion. Moreover, a correction work is necessary when the welded portion fails to pass a nondestructive inspection. This significantly increases the construction cost and the construction period disadvantageously. In addition, since a welding or cutting process is necessary, various types of equipment are also applied many times. This also increases energy consumption in the construction and adversely affects the environment.
As one of the diaphragm construction methods of the prior art, a HIBLADE process (registered trademark) has been employed in practical use. In this HIBLADE process (registered trademark), two pairs of cast steel integrated type external diaphragms (HIBLADEs) for upper and lower flanges are inserted into the steel pipe column. In addition, the upper and lower flanges of the steel H-beam are fixed to each external diaphragm by welding. The steel H-beam is cut out for a beam bracket for connecting to the steel pipe column. The upper and lower flanges of the beam bracket are welded to the HIBLADE, and a web of the beam bracket is welded to a rib plate installed in the column skin plate. The beam bracket and the steel H-beam are joined to each other with high-strength bolt friction connection. In such a HIBLADE, various techniques such as a shape having an excellent stress transfer property have been discussed.
However, in this HIBLADE process, a work for inserting the HIBLADE to the steel pipe column necessitates many processes and is also difficult in many cases. For this reason, in some cases, a special tool for inserting the HIBLADE to the steel pipe column is necessary. In addition, in this HIBLADE process, it is necessary to weld the HIBLADE to the upper and lower flanges of the steel H-beam. This increases the manufacturing labor and the manufacturing cost and delays the construction period disadvantageously as described above.
As one of the column and beam connection methods of the prior art, a high-strength bolt tension connection method is also employed in practical use. In this method, the steel pipe column and the steel H-beam are connected on the basis of high-strength bolt tension connection using a split tee or an end plate welded to a short section of the steel H-beam. Note that, when the split tee is employed, the flange of the split tee and the skin plate of the steel pipe column are joined on the basis of high-strength bolt tension connection, and the web of the split tee and the flange of the steel H-beam are joined on the basis of high-strength bolt friction connection. The web of the steel H-beam is joined to the rib plate installed in the steel pipe column on the basis of high-strength bolt friction connection as necessary.
However, in the high-strength bolt connection between the split tee or end plate and the steel pipe column, the steel pipe column has a closed cross section. Therefore, insertion and fastening of the high-strength bolts necessitate a lot of labor. Although a one-sided high-strength bolt or the like that can be inserted from one side is employed in practical use, this bolt is too expensive and has a limited strength. In addition, since bolt holes are to be fabricated in the steel pipe column, a special control device is necessary in order to secure positioning or accuracy of the bolt holes disadvantageously.
A technique of configuring the external diaphragm using a plurality of diaphragm segments has been discussed (for example, see Patent Document 1). However, in this technique discussed in Patent Document 1, the diaphragm segment is also welded to the steel pipe column. This increases the manufacturing labor and the manufacturing cost and delays the construction period disadvantageously as described above.
Patent Document 2 discusses an example in which a column-beam joint metal fitting like the diaphragm segment is combined to configure the external diaphragm in a similar manner. In this technique discussed in Patent Document 2, bolts are used for installation without welding the column-beam joint metal fitting to the steel pipe column. In addition, a filler such as mortar resin is filled in the column-beam joint metal fitting, so that stress is transferred using a bonding force of the filler and a shear capacity of the bolt. In the technique discussed in Patent Document 2, a welding process is not necessary to installation to the steel pipe column. Therefore, it is possible to prevent an increase of the manufacturing labor or the like advantageously.